1. Field of the Invention
The present application relates to a travelling wave amplifier, in particular, the present application relates to a differential circuit implemented within the travelling wave amplifier.
2. Background Art
Recent optical communication system provides an optical transmitter that performs the electric/optical signal conversion and the transmission of the converted optical signal by using a light source and an optical modulator such as Electro Absorption Modulator (EAM), Mach-Zehnder Modulator (MZM), and so on. In order to drive such optical modulators in high frequencies; a driver circuit with an arrangement of a traveling wave amplifier is often applied. Depending on types of the optical modulator, the driver is sometimes requested to output a modulation signal with amplitude of 2 to 8 V. The amplitude sometimes exceeds a breakdown voltage of transistors in the driver.